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The optimal selection of fracturing interval for the exploitation of tight oil reservoirs is very important for formulating a development program. In this study, the reservoir quality and the reservoir fracability are evaluated, and the criteria for the optimal selection of the fracturing interval are established, using the tight reservoir in the the Qing I Member of Qingshankou Formation in the Daqingzijing Oilfield of China as the study site. The results indicate that the porosity, the oil saturation and the effective thickness of tight reservoir are keys to optimizing the fracturing interval. The brittleness index and the difference coefficient among the horizontal stresses in the reservoir have a strong influence on fracability. The stress difference coefficient in the reservoir is smaller and the reservoir develops microfractures, the complex mesh fractures are easier to occur during fracturing. The stress difference between the reservoir and the surrounding bed is small and the thickness of the surrounding bed is thin, it is easy to communicate with adjacent oil-bearing layers when fracturing.

The potency of heteroatom-doping in reshaping optoelectronic properties arises from the distinct electronegativity variations between heteroatoms and carbon atoms. By incorporating two heteroatoms with differing electronegativities (e.g., B = N), not only is the architectural coherence of π-conjugated systems retained, but also dipolar traits are introduced, accompanied by unique intermolecular interactions absent in their all-carbon analogs. Another burgeoning doping strategy, featuring the heteroatom–boron–heteroatom motif (X–B–X, where X = N, O), has captured growing attention. This configuration's coexistence of the boron-heteroatom unit and an isolated heteroatom stimulates mutual modulation in the dipole of the boron-heteroatom unit and the heteroatom's electronegativity. In this Feature article, we present an encompassing survey of XBX-doped π-conjugated systems, elucidating how the integration of the X–B–X unit induces transformative structural and property changes within π-conjugated systems. [ABSTRACT FROM AUTHOR]

Metalloporphyrins and metallophthalocyanines emerge as popular building blocks to develop covalent organic nanosheets (CONs) for CO 2 reduction reaction (CO 2 RR). However, existing CONs predominantly yield CO, posing a challenge in achieving efficient methanol production through multielectron reduction. Here, ultrathin, cationic, and cobalt-phthalocyanine-based CONs (iminium-CONs) are reported for electrochemical CO 2 -to-CH 3 OH conversion. The integration of quaternary iminium groups enables the formation of ultrathin morphology with uniformly anchored cobalt active sites, which are pivotal for facilitating rapid multielectron transfer. Moreover, the cationic iminium-CONs exhibit a lower activity for hydrogen evolution side reaction. Consequently, iminium-CONs manifest significantly enhanced selectivity for methanol production, as evidenced by a remarkable 711% and 270% improvement in methanol partial current density (j CH3OH ) compared to pristine CoTAPc and neutral imine-CONs, respectively. Under optimized conditions, iminium-CONs deliver a high j CH3OH of 91.7 mA cm -2 at -0.78 V in a flow cell. Further, iminium-CONs achieve a global methanol Faradaic efficiency (FE CH3OH ) of 54% in a tandem device. Thanks to the single-site feature, the methanol is produced without the concurrent generation of other liquid byproducts. This work underscores the potential of cationic covalent organic nanosheets as a compelling platform for electrochemical six-electron reduction of CO 2 to methanol., (© 2023 Wiley‐VCH GmbH.)